Wafer oven



May 13, 1952 T1. F. NAYLOR ET A1.

WAFER OVEN 2 SHEETS--SHEET 1 Filed May 15, 1951 NP@ www Hdl- VigiliINVENToR.

www Erme/uf Grens/1( May 13,' 1952 J. F. NAYLOR ET AL WAFER OVENSHEETS--SHEET 2 Filed May l5, 1951 NVENTO Tan-PH FHM/ If MM5@ IDE/2R10(6459/9@ Patented May 13, 1952 NAFER OVEN YJoseph Francis Naylor andDerrick Greenen-Newton-le-Willows, England, assignors to '.i. & vT.Vicars' Limited, Newton-le-Willows, England, Va

:British comp any Application May 15, 1951, Serial Nogfl'i?, In GreatBritain May 3l., 1950 (Cl. 21S-35) -3 Claims. l

The present invention relates to an. improved oven for the baking ofwafers or the like confectionery products by means of a pair ofcooperating electrically heated plates.

In order to operate the oven with the plates ata predeterminedtemperature differential, it is known to provide the plates with apredetermined differential resistance value and to heat both plates froma common source of supply. In order, however, to yvary the temperaturedifferential during operation of the machine, it has hitherto beennecessary to heat each lplate from a separate source of supply.

It is an object of the present invention to provide an oven Vof the typeset forth in which the temperature differential may be varied duringoperation of the oven, both plates being heated from a common source ofsupply.

According to the present invention an oven of the type wherein a pair ofco-operating plates, to bake for example a wafer therebetween, areheated electrically from a common source of supply, is characterised bythe feature that the supply circuit to one of the plates is associatedwith a control mechanism to intermittently actuate a switch in saidcircuit to intermittently cut off power to said plate during a part ofthe period of operation of the oven, whereby the temperaturedifferential of the ,platesgis varied.

The 'switch is preferably automatically aco tuated responsive tovariation from apredetermined temperature differential of the plates.

The plates are preferably displaceable along Y an endless track, thesaid switch being mounted on one of the plates and actuated by a deviceadjacent the track.

The switch preferably includes a resiliently loaded member, and thedevice preferably comprises a strip member of adjustable operativelength disposed adjacent and parallel to part of the track in a positionto contact and depress the resiliently loaded member to actuate theswitch during that part of the cycle of displacement of the oven inwhich the oven passes adjacent the strip member. The strip memberpreferably comprises a displaceable endless belt having a run adjacentand parallel to the track and carrying a longitudinal raised stripportion over part only of its length, whereby the position of the stripportion relative to the belt (and so relative to the track) may bevaried to determine the operative length of said strip portion.

A plurality of interconnected pairs of plates may be mounted on theendless track and actuated in succession by-a common device. The sourceof supply is preferably Acarried bya triple bus-bar track,feach lbarcarrying one phase vof a three-phase current and each succeeding pair ofplates being provided with a pair of carbon brushes adapted to contact a`different pai-r of bus-bars.

The invention will be further described by way of example with referenceto the accompanying drawings in which:

Fig. 1 is a side elevation of a-preferred form of wafer oven accordingto the present invention, and

Fig, 2 is an electrical-circuit diagram for the oven assembly of Fig. l.

In the drawings pairsof separately electrically heated co-operatingplates I0, II forming a plurality of separate wafer ovens are mounted onrollers I2 and interconnected by links I3. The rollers ride in a .guidechannel I4 and around a driving wheelil which together define an endlesstrack for .the ovens. Thev driving wheel is suitably rotated,;by meansnot shown, to displace the plates along said endless track. *A source ofelectrical supplyfor thezovens is fed to .a ltriple bus-bar track, eachbus-bar I6 carrying one phase of a three-phasecurrent. `Each succeedingoven is provided with a p-air of carbon brushes II to contact adifferent pair of bus-bars, whereby to balance the loading on themulti-phase supply. Each plate II is'provdedwith a switch, for theheating elements therein, having'a resiliently loaded member I8. Adisplaceable endless belt I9 carried between sprockets 20, 2| has anupper run adjacent and parallel to a lower run of the ovens. The belt I9has a longitudinal raised strip portion 22 along half of its length. Oneof the sprockets ZIJ, 2| is rotatable (by means not shown) whereby theposition of the strip portion relative to the belt (and so relative tothe track) may be varied to determine the operative length of said stripportion.

In the electrical-circuit diagram shown in Fig. 2 of the drawings, leads23 introduce a threephase `50 cycle supply to a circuit breaker 2liwhich is connected by leads 25 to an auto-transformer 223. Theauto-transformer 26 is connected by leads 21 to a moving coil inductionregulator 28. The moving coil induction regulator 28 is connected to thebus-bars I6 by leads 2'8 one of which leads 29 passes first through acurrent transformer 30. The current transformer is connected by leads 3lto a watt meter (not shown).

The brushes I1 are connected by leads 32 to heating elements (not shown)in the plates I0,

H. The leads to the plates Il pass through the switch referred tohereinbefore and having the resiliently loaded member I8.

Leads 33 in the no-volt circuit of the circuit breaker 24 extend to doorswitches (not shown) for the oven assembly.

Leads 34 connect the moving coil induction regulator 28 to a watt metervoltage coil (not shown) and to push-button control switches (notshown).

In operation, the driving wheel 5 is rotated to displace the ovens alongthe endless track. The plates are electrically heated from a commonsource of supply and means of known type (not shown) periodicallyoperate to raise the plate H relative to the plate I to enable the ovensto be charged and emptied. The members |18 on the plate Il, during thelower run, contact and are actuated (to temporarily cut off power to theplate Il) by that part of the raised portion 22 which is disposed on theupper run of the belt I9.

It will be appreciated that the time, during which power to the plate Ilis cut off is proportional to the operative length of the raised portion22. Thus, during operation of the machine,

the temperature differential of the plates I0, Il

may be varied.

The operative length of the raised portion 22 may be variedautomatically responsive to variation from a predetermined temperaturedifferential of the plate.

We claim:

1. An oven including in combination a pair of co-operating electricheating plates, an endless track, means to displace the plates alongsaid endless track, an electrical supply circuit to said plates, aswitch in the supply circuit to one of said plates and mounted on saidone plate and having a resiliently loaded member, a strip memberdisposed adjacent and parallel to part of the track, and means to adjustthe operative length of said strip member, said strip member tointermittently contact and depress the resiliently loaded member toactuate the switch during that part of the cycle of displacement of theplates in which the plates pass adjacent the strip member, tointermittently cut off power to said one plate during said part of thecycle of displacement of the plates, whereby the temperaturedifferential of the plates is varied.

2. An oven including in combination a pair of co-operating electricheating plates, an endless track, means to displace the plates alongsaid endless track, an electrical supply circuit to said plates, aswitch in the supply circuit to one oi said plates and mounted on saidone plate and having a resiliently loaded member, an endless belt havinga run adjacent and parallel to the track, a longitudinal raised stripportion over part only of the length of the belt, and means to displacethe belt to adjust the operative length of said raised portion, saidraised portion to intermittently contact and depress the resilientlyloaded member to actuate the switch during that part of the cycle ofdisplacement of the plates in which the plates pass adjacent the raisedp0rtion, to intermittently cut off power to said one plate during saidpart of the cycle of displace ment oi the plates, whereby thetemperature differential of the plates is varied.

3. An oven assembly including in combination pairs of co-operatingelectric heating plates, means to interconnect in series said pairs ofplates, an endless track, means to displace the plates along saidendless track, an electrical supply circuit to said plates, a switch inthe supply circuit to one of each pair of plates and mounted on eachsaid one plate and each having a resiliently loaded member, a stripmember disposed adjacent and parallel to part of the track and means toadjust the operative length of said strip member, said strip member tointermittently contact and depress the resiliently loaded members toactuate the switches during that part of the cycle of displacement ofthe plates in which the plates pass adjacent the strip member, tointermittently cut o power to said one plates during said part of thecycle of displacement of the plates, whereby the temperature diierentialof the plates is varied.

JOSEPH FRANCIS NAYLOR. DERRICK GREENER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 797,6011 Perky Aug. 22, 19051,519,287 Woodson Dec. 16, 1924 1,557,004 Bates Oct. 13, 1925 1,584,825Tugendhat May 18, 1926 2,099,247 Whitlock Nov. 16, 1937

